Solvent-based adsorbent regeneration for onboard octane on-demand and cetane on-demand

ABSTRACT

A vehicular propulsion system, a vehicular fuel system and a method of producing fuel for an internal combustion engine. A separation unit that makes up a part of the fuel system includes one or more adsorbent-based reaction chambers to selectively receive and separate at least a portion of onboard fuel into octane-enhanced and cetane-enhanced components. Regeneration of an adsorbate takes place through interaction with a solvent, while subsequent separation allows the solvent to be reused. A controller may be used to determine a particular operational condition of the internal combustion engine such that the onboard fuel can be sent to one or more combustion chambers within the internal combustion engine without first passing through the separation unit, or instead to the separation unit in situations where the internal combustion engine may require an octane-rich or cetane-rich mixture.

BACKGROUND

The present disclosure relates generally to a vehicular fuel system forselectively separating an onboard fuel into octane-rich and cetane-richcomponents, and more particularly to such a system that promotesadsorption and solvent-based desorption as part of such onboard fuelseparation in such a way to reduce the size, weight and complexityassociated with such fuel separation activities.

SUMMARY

Within the realm of internal combustion engines (ICEs) used forvehicular propulsion, it is the four-cycle variant (with its intake,compression, combustion and exhaust strokes) that is most commonly inuse, where the combustion is typically achieved through either a sparkignition (SI) mode or compression ignition (CI) mode of operation. InSI-based modes, a mixture of air and fuel (typically octane-richgasoline) is introduced into a combustion chamber for compression andsubsequent ignition via spark plug. In CI-based modes, fuel (typicallycetane-rich diesel fuel) is introduced into the combustion chamber wherethe air is already present in a highly compressed form such that theelevated temperature within the chamber that accompanies the increasedpressure causes the fuel to auto-ignite. Of the two, the CI mode tendsto operate with greater efficiency, while the SI mode tends to operatewith lower emissions.

Various engine concepts or configurations may mimic the relatively lowemissions of an SI mode of operation while simultaneously satisfying thehigh efficiency operation of a CI mode of operation. Such concepts go byvarious names, and include gasoline direct injection compressionignition (GDCI), homogenous charge compression ignition (HCCI),reactivity controlled compression ignition (RCCI), as well as others. Inone form, a single fuel may be used, while in others, multiple fuels ofdiffering reactivities, usually in the form of selectiveoctane-enrichment or cetane-enrichment, may be introduced. Whileperforming octane on demand (OOD) or cetane on demand (COD) as a way offueling these engines is possible, such activities may be fraught withproblems. For example, having the respective octane-enriched orcetane-enriched portions be in either pre-separated form involves theparallel use of at least two onboard storage tanks and associateddelivery conduit. In addition, the time and complexity associated withvehicle refueling activity in this circumstance renders the possibilityof operator error significant. Likewise, OOD or COD generation once thesingle market fuel is already onboard may require distillation ormembrane-based permeation-evaporation (pervaporation) activities thatare accompanied by significant increases in size, weight and overallcomplexity of the onboard fuel-reforming infrastructure. Thesedifficulties are particularly acute as they relate to achieving a heatbalance associated with the underlying fuel enrichment activities. Assuch, a simplified approach to integrating such infrastructure into anonboard fuel separation system is warranted.

According to one embodiment of the present disclosure, a vehicularpropulsion system is disclosed. The propulsion system includes an ICEwith one or more combustion chambers and a fuel system for converting anonboard fuel into octane-rich and cetane-rich fuel components. The fuelsystem includes an onboard source of fuel in the form of a fuel supplytank (also referred to herein as an onboard fuel tank, main tank, marketfuel tank or the like), fuel conduit, a separation unit, a solventsupply, a solvent regeneration unit and a pair of enriched producttanks. The fuel conduit provides fluid connectivity between at leastsome of the fuel supply tank, separation unit and enriched producttanks. The separation unit includes one or more adsorbent-based reactionchambers that can selectively receive and separate at least a portion ofthe onboard fuel into an adsorbate and a remainder. The solvent supplyworks in conjunction with the separation unit such that one or moresolvents contained within the solvent supply may be brought into contactwith the adsorbate that forms in the reaction chambers such that thesolvent acts to convert at least a portion of the adsorbate into adesorbate so that the desorbed compound may be removed. After thesolvent removes the desorbate from the reaction chamber, thesolvent-desorbate mixture is introduced to a solvent regeneration unitthat can separate the solvent from the desorbate. In this way, theseparated desorbate may then be routed either to a first of the enrichedproduct tank for storage, or directly to the combustion chamber,depending on the need. A second of the enriched product tanks is fluidlycoupled to the reaction chamber (or chambers) for receiving andcontaining the remainder of the onboard fuel that did not get adsorbed.During operation of the ICE, the fuel system is in fluid communicationwith the ICE such that one or more of the supply tank and the first andsecond enriched product tanks provide their respective onboard fuel,separated desorbate and remainder to the one or more combustionchambers.

According to another embodiment of the present disclosure, a vehicularfuel system for converting an onboard fuel into octane-rich andcetane-rich components is disclosed. The fuel system includes a supplytank for containing the onboard fuel, fuel conduit in fluidcommunication with the supply tank, a separation unit in fluidcommunication with the supply tank through the fuel conduit, a solventsupply in fluid communication with the separation unit and containingone or more solvents to convert at least a portion of the adsorbate intoa desorbate, a solvent regeneration unit configured to separate at leasta portion of the solvent from the desorbate, and a pair of enrichedproduct tanks the first of which receives and contains the portion ofthe desorbate that has been separated from the one or more solvents, anda second of which receives and contains the non-adsorbed remainder fromthe onboard supply of fuel that was delivered to one or moreadsorbent-based reaction chambers that make up the separation unit.

According to yet another embodiment of the present disclosure, a methodof producing fuel that is used in an ICE to provide propulsive power toa vehicle is disclosed. The method includes conveying an onboard (thatis to say, market) fuel to a separation unit, contacting the fuel withan adsorbent situated within the separation unit such that at least someof the fuel is converted into an adsorbate and at least some of the fuelis converted into a remainder, reacting one or more solvents with theadsorbate such that at least some of the adsorbate is converted into adesorbate, separating the desorbate from the solvent or solvents, andconveying one or more of the onboard fuel, separated desorbate andremainder to a combustion chamber within the ICE.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The following detailed description of specific embodiments of thepresent disclosure can be best understood when read in conjunction withthe following drawings, where like structure is indicated with likereference numerals and in which:

FIG. 1 shows a vehicle with a partial cutaway view of an engine inaccordance with one or more embodiments shown or described;

FIG. 2 shows a simplified cutaway view of a cylinder of the engine ofFIG. 1 along with a controller in accordance with one or moreembodiments shown or described; and

FIG. 3 illustrates a simplified view of an onboard fuel separationsystem in accordance with one or more embodiments shown or described.

DETAILED DESCRIPTION

In the present disclosure, a fuel system with adsorption-basedseparation may be used to first split an onboard fuel into OOD or CODstreams and then to regenerate the adsorbent by solvent desorption ofthe adsorbate. Within the present context, the term “adsorbate” and itsvariants include those portions of the onboard fuel that interact bysurface retention (rather than by bulk absorption) with the adsorbent,while the term “desorbate” and its variants include those portions ofthe adsorbate that are subsequently liberated from the adsorbent as aresult of the solvent-based regenerating action. The adsorption can takeadvantage of one or both of two specific mechanisms: (1) employingdiffering functional groups that attract specific adsorbates (such asaromatics, cyclic and optional oxygenates) that are present in theonboard fuel supply in what is referred to in the present disclosure asan affinity-based adsorbent; and (2) using a molecular sieve toselectively pass certain smaller (that is to say, linear) moleculeswhile retaining larger (that is to say, branched) ones in what isreferred to in the present disclosure as a size selective-basedadsorbent. Examples of the first type of adsorbent include activatedcarbon, silica, and alumina, as well as some types of zeolites andfunctionalized porous material in general, while examples of the secondtype include zeolites, metal organic frameworks and structured porousmaterial. Accordingly, the type of sorbent material used for aparticular adsorption reaction may be based on the way the sorbentfunctions where affinity-based sorbents are useful for generatingoctane-rich fuel components from the market fuel owing at least in partto the specific functionality (oxygen atom, aromatic, or double bond)attributes of such components. As such, affinity-based adsorbents usethis functionality to preferentially capture octane-rich fuelcomponents. It is noted that there are some high cetane number (CN)additives that have functional groups such that if present in the marketfuel, the affinity-based sorbents could capture them as well;nevertheless, the presence of such materials is deemed to be low enoughto not significantly impede the ability of affinity-based adsorbents toprovide an adsorbate with a higher research octane number (RON) thanthat present in the market fuel. Likewise, size selective-based sorbentsare preferred for generating cetane-rich fuel components because of thelinear structure (and relatively small molecular footprint) of alkanesand other such components in commercial fuels. As such, sizeselective-based adsorbents take advantage of the relatively smallaromatics with single benzene rings (such as benzene, toluene andxylene) that are prevalent in gasoline and the larger aromatics in theform of polycyclic (or polynuclear) aromatic hydrocarbons (PAHs)including naphthalene and its derivatives in diesel fuel topreferentially capture cetane-rich fuel components.

Referring initially to FIG. 3, details associated with the use ofsolvent-based desorption for performing onboard COD and OOD operationswhile avoiding complicated component redundancy for fuel system 200 areshown. By taking advantage of existing onboard fuel delivery and ICE 150operating infrastructure, any on-vehicle adsorbing and regeneratingactivities can be achieved without requiring additional heating orcooling equipment or efficiency-decreasing activities such as thoseassociated with the high pressure operation of membrane-basedpervaporation equipment. The fuel system 200 includes a network ofpipes, tubing or related flow channels—along with various valves topreferentially permit or inhibit the flow of the onboard fuel and itsbyproducts of fuels, depending on the need—that make up conduit 210. Thesolvent supply 230 is coupled to the market fuel M being delivered fromthe tank 220 through conduit 210 so that if the market fuel M that isbeing delivered to either the combustion chamber 156 or separation unit240 is in need of being enriched with either octane or cetane, it canreceive such enrichment from the cooperation of the solvent supply 230and the separation unit 240. In one form, the solvent supply 230 mayinclude a solvent tank 232 for holding an eluent in the form of solventV such as ethylene glycol, propylene carbonate or the like, while a pump234 may be used to pressurize and deliver the solvent V contained in thesolvent tank 232 to the reaction chambers 242, 244 of separation unit240.

Within the present context, a remainder R (also referred to as afiltrate) is the portion of the market fuel M being exposed to theadsorbent 242A, 244A in the reaction chambers 242, 244 that does not getadsorbed, such as through one or both of the previously-discussedfunctional group or molecular sieve modes of adsorbent 242A, 244Aoperation. Likewise, the adsorbate A (also referred to as an eluate) isthe portion of the market fuel M being exposed to the adsorbent 242A,244A in the reaction chambers 242, 244 that does get adsorbed, while thesolvent V used to desorb the adsorbate A is referred to as the eluent.In addition, a fuel is deemed to be octane-rich when it has aconcentration of octane (C₈H₁₈) or related anti-knocking agent that isgreater than that of the commercially-available market fuel M from whichone or more separation activities discussed herein have been employed.By way of example, a fuel would be considered to be octane-rich if ithad a RON of greater than about 91-92 or an anti-knock index (AKI) ofgreater than about 85-87 for a so-called regular grade unleaded fuel,with respectively slightly higher values for mid-grade unleaded fuel andpremium unleaded fuel. It will be understood that there are regionalvariations in the values of RON, AKI or other octane indicia, and thatthe ones expressly discussed in the previous sentence contemplate aUnited States market. Nevertheless, such values will be understood to besuitably adjusted to take into consideration these regional variations,and that all such values are deemed to be within the scope of thepresent disclosure within their respective region, country or relatedjurisdiction. As with octane, a fuel is deemed to be cetane-rich when ithas a concentration of cetane (C₁₆H₃₄) that is greater than that of thecommercially-available market fuel M. By way of example, a fuel would beconsidered to be cetane-rich if it had a CN of greater than about 40-45as understood in the United States market, with suitable variationselsewhere.

Referring next to FIG. 1, a vehicle 100 includes a chassis 110 with aplurality of wheels 120. Chassis 110 may either be of body-on-frame orunibody construction, and both configurations are deemed to be withinthe scope of the present disclosure. The passenger compartment 130 isformed inside the chassis 110 and serves not only as a place totransport passengers and cargo, but also as a place from which a drivermay operate vehicle 100. A guidance apparatus (which may include, amongother things, steering wheel, accelerator, brakes or the like) 140 isused in cooperation with the chassis 110 and wheels 120 and othersystems to control movement of the vehicle 100. An ICE 150 is situatedwithin an engine compartment in or on the chassis 110 to providepropulsive power to the vehicle 100 while a controller 170 interactswith ICE 150 to provide instructions for the latter's operation.

Referring next to FIG. 2, details associated with the structure andoperation of a portion of the ICE 150 and the controller 170 are shown.The ICE 150 includes an engine block 151 with numerous cylinders 152, acrankshaft 153 rotatably movable within the block 151, numerous cams 154responsive to movement of the crankshaft 153, a head 155 coupled to theengine block 151 to define numerous combustion chambers 156. The head155 includes inlet valves 157 and exhaust valves 158 (only one of eachis shown) that in one form may be spring-biased to move in response tothe crankshaft 153 through a corresponding one of the cams 154 that arecontrolled by either a crankshaft-driven chain, crankshaft-actuatedpushrods or pneumatic actuators (none of which are shown). An air inlet159 and an exhaust gas outlet 160 are in selective fluid communicationwith each of the combustion chambers 156 through a fuel injector 161,while a piston 162 is received in each respective cylinder 152 andcoupled to the crankshaft 153 through a connecting rod 163 so that thereciprocating movement of the piston 162 in response to an SI or CIcombustion taking place within the combustion chamber 156 is convertedby the pivoting movement of the connecting rod 163 and crankshaft 153 torotational movement of the crankshaft 153 for subsequent power deliveryto the remainder of a powertrain that is made up of the ICE 150 andtransmission, axles, differentials (none of which are shown) and wheels120. Although ICE 150 is shown without a spark ignition device (such asa spark plug) in a manner consistent with the various CI-based engineconfigurations (such as RCCI, HCCI or the like), it will be understoodthat in certain operating loads or conditions such as low loads, coldstarts and associated warm-ups, such a spark ignition may be used(possibly in conjunction with some throttling) to increase the flamepropagation combustion rate while keeping lower cylinder pressures.

In one form, ICE 150 is configured as a gasoline compression ignition(GCI) engine that can be operated with a gasoline-based fuel. In suchcase, the presently-disclosed fuel system may be used to achieve CODthrough operation on various fuels, including market gasoline, gasolinewithout an oxygenate or related anti-knock compound (also referred to asbase gasoline) or gasoline with one of the many types of alkyls,aromatics or alcohols. In one non-limiting example, such fuel may have aboiling temperature in the range of ambient to about 200° C. Unlike anSI mode of operation where the fuel is substantially injected during thefour-cycle operation's inlet stroke, a GCI mode substantially injectsthe fuel during the compression stroke. In one form, the fuel and airare not fully mixed, which permits phasing of the combustion process tobe controlled by the injection process. Moreover, the ignition delaypermitted by gasoline-based fuels versus diesel-based fuels will allowfor the partially premixed fuel and air to become more mixed duringcompression, which in turn will leave to improvements in combustion. Agasoline-based market fuel M with some amount of fuel and air premixinghelps ensure suitable fuel-air equivalence ratios for various engineloads and associated fuel injection timing scenarios. Thus, whenconfigured as a GCI engine, ICE 150 using a fuel in the gasolineautoignition range (where for example, the RON is greater than about 60and the CN is less than about 30) can provide relatively long ignitiondelay times compared to conventional diesel fuels. This in turn can leadto improved fuel-air mixing and related engine efficiency, along withlower soot and NOx formation; this latter improvement leads in turn to asimplified exhaust gas treatment system since the emphasis is now onoxidizing hydrocarbons and carbon monoxide in an oxygen-rich environmentrather than trying to simultaneously control NOx and soot. Moreover,when operated as a GCI engine, ICE 150 requires lower fuel injectionpressures than diesel-based CI engines.

Furthermore, when configured as a GCI engine, ICE 150 may take advantageof the market fuel M that is in gasoline form, especially when such fuelrequires lower amounts of processing; in one form (for example, when themarket fuel M has an intermediate RON of between about 70 and 85. Suchoctane concentrations could then be adjusted via OOD or COD through theoperation of the fuel system 200 that is discussed in more detailelsewhere in this disclosure.

Moreover, unlike HCCI modes of operation where the fuel and air is fullypremixed prior to introduction into the combustion chamber 156, the GCIembodiment of ICE 150 will permit CI operation under higher engine loadsand compression ratios without concern over engine knocking.Furthermore, by permitting in-cycle control of the combustion phasing,an ICE 150 configured as a GCI can take advantage of fuel injectiontiming in order to make it easier to control the combustion processcompared to an HCCI configuration where the combination of temperatureand pressure inside the cylinder may not be precisely known.

In another form, ICE 150 may be configured as an SI engine that can beoperated with a gasoline-based fuel. In this case, thepresently-disclosed fuel system may be used to achieve OOD throughoperation on various fuels, including market gasoline, gasoline withoutan oxygenate or related anti-knock compound or gasoline with one of themany types of alkyls, aromatics or alcohols. In another form, ICE 150 isconfigured as a CI engine that can be operated with a diesel-based fuel.In this case, the presently-disclosed fuel system 200 may be used toachieve COD through the use of suitable regenerative solvent-based,affinity-based and size selective-based adsorbents 242A, 244A.

Controller 170 is used to receive data from sensors S and providelogic-based instructions to the various parts of the fuel system 200that will be discussed in more detail below. As will be appreciated bythose skilled in the art, controller 170 may be a singular unit such asshown notionally in FIGS. 1 through 3, or one of a distributed set ofunits (not shown) throughout the vehicle 100. In one configuration,controller 170 may be configured to have a more discrete set ofoperational capabilities associated with a smaller number of componentfunctions such as those associated solely with the operation of the fuelsystem 200. In such a configuration associated with only performingfunctions related to operation of the fuel system 200, the controller170 may be configured as an application-specific integrated circuit(ASIC). In another configuration, controller 170 may have a morecomprehensive capability such that it acts to control a larger number ofcomponents, such as the ICE 150, either in conjunction with orseparately from the fuel system 200. In this configuration, thecontroller 170 may be embodied as one or more electronic control units(ECUs). It will be appreciated that ASICs, ECUs and their variants,regardless of the construction and range of functions performed by thecontroller 170, are deemed to be within the scope of the presentdisclosure.

In one form, controller 170 is provided with one or more input/output(I/O) 170A, microprocessor or central processing unit (CPU) 170B,read-only memory (ROM) 170C, random-access memory (RAM) 170D, which arerespectively connected by a bus 170E to provide connectivity for a logiccircuit for the receipt of signal-based data, as well as the sending ofcommands or related instructions to one or more of the components withinICE 150, one or more components within fuel system 200, as well as othercomponents within vehicle 100 that are responsive to signal-basedinstructions. Various algorithms and related control logic may be storedin the ROM 170C or RAM 170D in manners known to those skilled in theart. Such control logic may be embodied in a preprogrammed algorithm orrelated program code that can be operated on by controller 170 such thatits instructions may then be conveyed via I/O 170A to the fuel system200. In one form of I/O 170A, signals from the various sensors S areexchanged with controller 170. Sensors S may comprise level sensors,pressure sensors, temperature sensors, optical sensors, acousticsensors, infrared sensors, microwave sensors, timers or other sensorsknown in the art for receiving one or more parameters associated withthe operation of ICE 150, fuel system 200 and related vehicularcomponents. For example, one or more sensors S may be used to determineif a minimum threshold level of an octane-rich fuel component or acetane-rich fuel component is present in a pair of enriched producttanks 250, 260. Although not shown, controller 170 may be coupled toother operability components for vehicle 100, including those associatedwith movement and stability control operations, while additional wiringsuch as that associated with a controller area network (CAN) bus (whichmay cooperate with or otherwise be formed as part of bus 170E) may alsobe included in situations where controller 170 is formed from variousdistributed units.

In situations where the controller 170 is configured to provide controlto more than just the fuel system 200 (for example, to the operation ofone or more of the ICE 150 or other systems within vehicle 100), othersuch signals from additional sensors S may also be signally provided tocontroller 170 for suitable processing by its control logic; one suchexample may include those signals where combustion data from the ICE 150is provided for control over the mixing or related delivery of the fueland air. Likewise, in a manner consistent with various modes of ICE 150operation, controller 170 may be programmed with drivers for variouscomponents within ICE 150, including a fuel injector driver 170F, aspark plug driver (for SI modes of operation) 170G, engine valve control170H and others (not shown) that can be used to help provide the variousforms of fuel introduction to the combustion chamber 156, includingthose associated with a multiple-late-injection, stratified-mixture,low-temperature combustion (LTC) process as a way to promote smoothoperation and low NOx emissions of ICE 150 over a substantial entiretyof its load-speed range. Within the present context, load-speed mappingof ICE 150 may be used to identify operating regions such as those usedduring cold starts and ICE 150 warm-up, low ICE 150 loads, medium ICE150 loads and high ICE 150 loads, where correspondingly lower amounts ofexhaust gas re-breathing takes place through manipulating the overlap ofthe intake valve 157 relative to the exhaust valve 158, possibly inconjunction with other approaches such as exhaust gas recirculation(EGR) to help provide one or more of combustion control, exhaust gasemission reductions, or other operability tailoring for ICE 150.

In addition to providing instructions for combustion control, emissionreductions or the like, the controller 170 interacts with one or morevarious components that make up conduit 210, including variousactuators, valves and related components to control the operation of thedelivery of fuel from an onboard fuel supply tank 220 that acts as themain tank for the storage of the market fuel M (for example,conventional or even low-grade gasoline, solvent supply 230 andseparation unit 240 (all as shown and described in more detail inconjunction with FIG. 3) in order to effect the production of OOD or CODrequired to operate ICE 150 for a given set of load and relatedoperating conditions. In one form of CAN, the controller 170 couldmanage the fuel flow from either the fuel supply tank 220 or theenriched product tanks 250, 260 to the combustion chamber 156 where thetwo fuels corresponding to OOD or COD are injected separately, or byblending prior to being introduced into the combustion chamber 156 atdifferent ratios depending on load, speed and other optional parametersassociated with operation of ICE 150.

Significantly, controller 170 is useful in promoting customizable fuelinjection and subsequent combustion strategies for various ICE 150configurations where a CI mode of operation is used. For example, whenused in conjunction with a GCI-based (that is to say, PPCI-based) mode,the controller 170 may instruct the fuel to be injected in a stagedmanner late in the compression phase of the four-cycle operation of ICE150. In this way, the fuel charge may be thought of as having bothlocally stoichiometric and globally stratified properties.Significantly, because an octane-rich fuel (for example, gasoline) has ahigher volatility and longer ignition delay relative to a cetane-richfuel (for example, diesel), by introducing the octane-rich fuel into thecombustion chamber 156 relatively late in the compression stroke andtaking advantage of the fuel's inherent ignition delay (which helps topromote additional fuel-air mixing), combustion does not commence untilafter the end of the injection. To achieve a desirable degree ofstratification, multiple injections may be used. By operating under thelow temperature combustion (LTC) conditions that are associated withstratified fuel combustion, a GCI mode of operation can havesignificantly reduced NOx production and soot emissions while achievingtraditional diesel-like CI mode thermal efficiencies. Moreover, such anapproach permits the vehicle 100 to use a version of the onboard marketfuel M with a lower octane than would otherwise be used. This isbeneficial in that such fuel requires a smaller amount of processingthan conventional gasoline and diesel fuels; this in turn reduces thecost as well as entire well-to-tank emissions of other undesirablesubstances, such as CO₂.

In addition to a GCI mode of operation, such instructions as provided bycontroller 170 are particularly beneficial for the multiple-lateinjection strategy used for the delivery of fuel in HCCI, RCCI orrelated modes of operation of ICE 150, as such delivery may be optimizedwhen made to coincide with various sequences in the compression strokethat can be measured by sensors S as they detect crank angle degree(CAD) values from the crankshaft 153 to help control when auto-ignitionoccurs. Within the present context, the position of the piston 162within the cylinder 152 is typically described with reference to CADbefore or after the top dead center (TDC) position of piston 162. Thecontroller 170 may also base such delivery strategies on other ICE 150operating parameters such as the previously-mentioned load and enginespeed, as well as the number of times such injection is contemplated.For example, CAD from 0° to 180° corresponds to the power stroke, with0° representing TDC and 180° representing bottom dead center (BDC).Likewise, CAD from 180° to 360° represents an exhaust stroke with thelatter representing TDC. Moreover, CAD from 360° to 540° represents anintake stroke with BDC at the latter. Furthermore, CAD from 540° to 720°represents a compression stroke with TDC at the latter. By way ofexample, the controller 170—when used in a 6-cylinder engine—would haveignition taking place every 120° of crankshaft 153 rotation, that is tosay three ignitions per every revolution of ICE 150. Thus, when ignitionhas taken place each of the six cylinders one time, the crankshaft 153has rotated twice to traverse 720° of rotary movement. Likewise, if ICE150 were configured as a 4-cylinder engine, the ignition would takeplace every 180° of crankshaft 153 rotation.

In one form, one of the sensors S may be a crank sensor to monitor theposition or rotational speed of the crankshaft 153. The data acquiredfrom such a crank sensor is routed to the controller 170 for processingin order to determine fuel injection timing and other ICE 150parameters, including ignition timing for those circumstances (such ascold startup, and the ensuing warm-up) where a spark ignition device isbeing used. Sensors S such as the crank sensor may be used incombination with other sensors S (such as those associated with valve157, 158 position) to monitor the relationship between the valves 157,158 and pistons 162 in ICE 150 configurations with variable valvetiming. Such timing is useful in CI modes of operation of ICE 150 inthat it can close the exhaust valves 158 earlier in the exhaust strokewhile closing the intake (or inlet) valves 157 earlier in the intakestroke; such operation as implemented by controller 170 can be used toadjust the effective compression ratio of ICE 150 in order to obtain therequired temperature and pressure associated with CI combustion.Likewise, when SI combustion is required, the controller 170 mayinstruct the valves 157, 158 to reduce the compression ratio consistentwith an SI mode of operation. Furthermore, the controller 170may—depending on the need of ICE 150—provide auxiliary sparking throughSI driver 170G for fuel preparation (such as the generation of freeradicals in the air-fuel mixture). Sensed input (such as that fromvarious locations within ICE 150, including CAD from the crankshaft 153,as well as those from driver-based input such as the accelerator ofguidance apparatus 140) may be used to provide load indicia. Likewise,in addition to suitable adjustment of the valves 157, 158, balanced fueldelivery from each of the enriched product tanks 250, 260 withpressurizing forces provided by one or more fuel pumps 270 may beachieved by controller 170 depending on if ICE 150 is in a CI mode or anSI mode of operation.

In one form, the fuel injection pressures generated by the fuel system200 may be up to about 500 bar for gasoline direct injection, and up toabout 2500 bar for common rail diesel injection where this higherinjection pressure is used to expand the operating region ofdiesel-based CI engines in that it facilitates premixed CI combustion.In so doing, this latter pressure increase for diesel fuel-based enginesmay offset the needed robustness of construction and reductions incompression ratio and fuel ignition delay. Although there is only pump270 shown (immediately upstream of the ICE 150) in an attempt to keepvisual clarity within the figure, it will be appreciated that additionalpumps 270 may be placed in other locations within conduit 210 in orderto facilitate the flow of fuel through the fuel system 200, and that allsuch variants are within the scope of the present disclosure. Inaddition, the pressure of the fuel being introduced via pump 270 can bevaried, and as such may be varied by controller 170 to regulate overallfuel system 200 performance. For instance, higher injected fuelpressures can promote a more thorough octane-enhanced adsorptionprocess.

The controller 170 may be implemented using model predictive controlschemes such as the supervisory model predictive control (SMPC) schemeor its variants, or such as multiple-input and multiple-output (MIMO)protocols, where inputs include numerous values associated with thevarious measurements that may be acquired by sensors S, as well as ofestimated values (such as from the lookup tables or calculatedalgorithmically) based on parameters stored in ROM 130C or RAM 130D orthe like. In that way, an output voltage associated with the one or moresensed values from sensors S is received by the controller 170 and thendigitized and compared to a predetermined table, map, matrix oralgorithmic value so that based on the differences, outputs indicativeof a certain operating environment for ICE 150 are generated. Theseoutputs can be used for adjustment in the various components theoperation of which falls within the purview of the controller 170, suchas the remaining components associated with fuel system 200, as well asfor adjusting whether fuel delivered from the fuel system 200 to thecombustion chamber 156 corresponds to a bypass condition (as isdiscussed in more detail elsewhere within the present disclosure) of theICE 150 or an adsorption condition environment of the ICE 150.

As mentioned above, in one form, controller 170 may be preloaded withvarious parameters (such as atmospheric pressure, ambient airtemperature and flow rate, exhaust gas temperature and flow rate or thelike) into a lookup table that can be included in ROM 170C or RAM 170D.In another form, controller 170 may include one or more equation- orformula-based algorithms that permit the processor 170B to generate asuitable logic-based control signal based on inputs from various sensorsS, while in yet another form, controller 170 may include both lookuptable and algorithm features to promote its monitoring and controlfunctions. Regardless of which of these forms of data and computationinteraction are employed, the controller 170—along with the associatedsensors S and conduit 210—cooperate such that as an operating load onthe ICE 150 varies, a suitable adjustment of the market fuel M that ispresent in the onboard fuel supply tank 220 may be made to provide theamount of octane or cetane enrichment needed for such operating load bymixing the onboard market fuel M with one or the other of thehigh-octane or high-cetane product fuels from the enriched product tanks250, 260.

One operational parameter of ICE 150 that may be preloaded into orgenerated by controller 170 is the mean effective pressure (MEP). In oneform, MEP may be used to correlate ICE 150 operating regimes to fuelneeds and the various forms of multiple-late injection strategiesdiscussed previously for various CI mode configurations. MEP—includingits variants indicated mean effective pressure (IMEP), brake meaneffective pressure (BMEP) or friction mean effective pressure(FMEP)—provides a measure of the ability of a particular ICE 150 to dowork without regard to the number of cylinders 152 or displacement ofsuch cylinders 152. Moreover, it provides a measure of the pressurecorresponding to the torque produced so that it may be thought of as theaverage pressure acting on a piston 162 during the different portions ofits inlet, compression, ignition and exhaust cycles. In fact, MEP isoften considered a better parameter than torque to compare engines fordesign and output because of its independence from engine speed or size.As such, MEP provides a better indicator than other metrics (such ashorsepower) for engines in that the torque produced is a function of MEPand displacement only, while horsepower is a function of torque and rpm.Thus, for a given displacement, a higher maximum MEP means that moretorque is being generated, while for a given torque, a higher maximumMEP means that it is being achieved from a smaller ICE 150. Likewise,higher maximum MEP may be correlated to higher stresses and temperaturesin the ICE 150 which in turn provide an indication of either ICE 150life or the degree of additional structural reinforcement.Significantly, extensive dynamometer testing, coupled with suitableanalytical predictions, permit MEP to be well-known for modern enginedesigns. As such, for a CI mode, MEP values of about 7.0 bar to about9.0 bar are typical at engine speeds that correspond to maximum torque(around 3000 rpm), while for naturally aspirated (that is to say,non-turbocharged) SI modes, MEP values of about 8.5 bar to about 10.5bar are common, while for turbocharged SI modes, the MEP might bebetween about 12.5 bar and about 17.0 bar.

Likewise, MEP values may be determined for various load-relatedoperating regimes for ICE 150. Such operating regimes may include lowpower or load (including, for example, engine idling conditions) that inone form corresponds to a MEP of up to about 1.0 bar, in another form ofan MEP of up to about 2.0 bar. Likewise, such operating regimes mayinclude normal (or medium) power or load that is one form corresponds toa MEP of between about 2.0 bar to about 5.0 bar, in another form of anMEP of between about 2.0 bar and about 6.0 bar, in another form of anMEP of between about 2.0 bar and about 7.0 bar. Moreover, such operatingregimes may include a high power or load that is one form corresponds toa MEP of about 7.0 bar and above, in another form of an MEP of about 8.0bar and above, in another form of an MEP of about 9.0 bar and above, andin another form of an MEP of about 10.0 bar and above.

As will be understood, these and other MEP values may be input into asuitably-mapped set of parameters through load-speed mapping or the likethat may be stored in a memory accessible location (such as the lookuptables mentioned previously) so that these values may be used to adjustvarious ICE 150 operating parameters, as well as for the controller 170when acting in a diagnostic capacity. In such case, it may work inconjunction with some of the sensors S, including those that can be usedto measure cylinder 152 volume (such as through crankshaft 153 angle orthe like).

Referring again to FIG. 3, in one form, the solvent supply 230 is a partof a closed-loop such that the solvent V can be reused. Within thepresent context, a closed-loop solvent approach includes thoseconfigurations where the solvent V that is used to desorb the adsorbateA can be regenerated and substantially recaptured for reuse rather thanrelying on a regular addition of solvent V from an external supply.Being closed-loop does not necessitate complete fluid isolation betweenthe solvent V that is routed through solvent conduit 238 and the onboardflow of market fuel M that is routed through conduit 210. In fact, asdescribed elsewhere, fluid interaction between the solvent V traversingconduit 238 and the onboard fuel traversing conduit 210—while eachdefining different starting and ending locations from one another—takesplace at the reaction chambers 242, 244 that act as a common receivinglocation for the respective fluids. As such, a small amount of the fluidthat makes up solvent V may be permitted to escape through the commonspace defined by the reaction chambers 242, 244 and still be deemed tobe within the scope of a closed-loop solvent architecture.

To accomplish this closed-loop retention of the desorbing solvent V, asolvent regeneration unit 236 is formed as part of solvent supply 230 topermit the solvent V to be separated and returned to the tank 232through solvent conduit 238 in a one-step process. In one form, thesolvent regeneration unit 236 may operate by liquid-liquid extraction(also referred to as solvent extraction), where the desorbing solvent Vis separated through combination with another immiscible solvent suchthat a multilayer compound develops based on differences in theirsolubilities. In another form, the solvent regeneration unit 236 mayoperate by extractive distillation. Such extractive distillation may beespecially useful in situations where the difference in volatilitybetween the solvent V and the desorbate D is small. In this latter form,a relatively non-volatile (that is to say, high boiling point)separation solvent is introduced into the solvent supply 230 in such away to cause the relative volatilities to change between it and thedesorbing solvent V such that each of them may be subsequently separatedby conventional distillation activities.

Regardless of how the solvent V is regenerated within the solvent supply230, the solvent elution-based process as discussed herein allows thesolvent V to wash the adsorbate A from the reaction chambers 242, 244.In one form, the solvent V is made to flow past the adsorbate A andadsorbent 242A, 244A that in one form defines a surface of the reactionchambers 242, 244 such that the eluting power of the solvent V forcesthe displacement of the adsorbate A from the adsorbent 242A, 244A. Thus,the use of solvent V such as ethylene glycol, propylene carbonate or thelike is such that when the solvent V is circulated into the separationunit 240 through the solvent supply 230, the high affinity of suchsolvent V for the adsorbate A portion of the market fuel M that isformed on the adsorbent 242A, 244A, coupled with the low affinity of thesolvent V for the material that makes up the adsorbent 242A, 244A,promotes a significant elution force that in turn causes displacement ofsuch adsorbate A from the adsorbent 242A, 244A. In one form, any excesssolvent V remaining on the adsorbent 242A, 244A within the reactionchambers 242, 244 may be recovered by methods such as heating theadsorbent 242A, 244A or passing air or steam to evaporate the solvent Vfollowed by condensation.

As a result of the reaction between the adsorbate A and the solvent Vthat is being introduced from the solvent supply 230 to the separationunit 240, at least a portion of the adsorbed compounds or related agentsthat are on the exposed one of the reaction chambers 242, 244 arereleased in the form of desorbate D. After this, the solvent V andliberated desorbate D may be carried away through the conduit 238 thatmakes up the solvent supply 230 in order to have the solvent Vregenerated. This regeneration results in a separation of the solvent Vfrom the desorbate that is now a suitable octane-enriched orcetane-enriched fuel component E_(O), E_(C). The controller 170 may thencooperate with conduit 210 to ensure that the octane-enriched orcetane-enriched fuel component E_(O), E_(C) is introduced into thecombustion chamber 156 if the driving cycle or limited supply ofsuitably-enriched fuel components within the respective enriched producttanks 250, 260 warrants it, or otherwise routed to a respective one ofthe enriched product tanks 250, 260 where such fuel component can bestored until needed.

In one form, a batch-like processing approach may be made to take placewithin the separation unit 240 where the pair of reaction chambers 242,244 are placed in fluid communication with the solvent supply 230 suchthat the market fuel M that becomes adsorbed in a respective one of thereaction chambers 242, 244 may be subsequently desorbed by the chemicalinteraction of the solvent V in the solvent supply 230 as previouslydiscussed. By having at least two reaction chambers 242, 244, theseparation unit 240 may be operated in a parallel manner such that whileone of the reaction chambers 242, 244 is being used with its respectiveadsorbent 242A, 244A to preferentially capture the adsorbate A, theother of the reaction chambers 242, 244 may be exposed to the solvent Vfrom the solvent supply 230 in order to perform the desorbing or elutionoperation, after which the roles of the two chambers 242, 244 arereversed through manipulation by controller 170 of valves (not shown)that make up part of conduit 238, 210. After exposure of the adsorbate Ato the solvent V such that both the desorbate D and portions of thesolvent V are removed from the separation unit 240, the respective oneof the adsorption chambers 242, 244 is regenerated and ready for anotherbatch of incoming market fuel M for processing. This removal of thesolvent V and adsorbate A has the tendency of keeping the adsorptionchambers 242, 244 at a mild temperature, which is beneficial in that itavoids the need to reheat the first and second reaction chambers 242,244 during each regeneration stage. Significantly, the use of solvent Vmeans that the need to use heating as a way to desorb the adsorbate Acan be avoided, thereby reducing the number and complexity of componentsused with or as part of the fuel system 200. In a related way, when theeluent (solvent V) and the eluate (adsorbate A) are separated remotelyfrom the reaction chambers 242, 244 (such as when taking place insolvent regenerator 236), the reaction chambers 242, 244 are furtherkept at a mild temperature, which eliminates the need to re-heat suchchambers during each regeneration stage.

Eventually, the adsorbent 242A, 244A reaches a state where it can nolonger capture any additional adsorbate A; resulting in a saturatedstate for the adsorbent 242A, 244A. The controller 170 can be used inconjunction with one or more of the sensors S to determine the amount ofadsorbate A production within the fuel system 200, particularly as itrelates to the desired degree of saturation. For example, by detecting aconcentration difference between the market fuel M stream that isentering into the separation unit 240 and that leaving the separationunit 240, the logic contained within the controller 170 may determinethat a certain value of such concentration difference can be correlatedto a degree of adsorbate A saturation of the adsorbent 242A, 244A.Regardless of the mechanism used, when saturated adsorbent 242A, 244A isreached, the controller 170 adjusts various valves that are formedwithin conduit 210 in order to selectively adsorb or desorb theadsorbate A. Within the present context, the adsorbent 242A, 244A isconsidered to be unsaturated when it is still capable capturing ameasurable quantity of the adsorbate A.

In using the solvent supply 230, the controller 170 may instructbatch-based switching between the two chambers 242, 244 through one ofthree different techniques. In a first technique, a sensor S isconnected to the exit of the first reaction chamber 242 such that whenthe inlet and outlet liquid streams of the first reaction chamber 242have an equal aromatic content as detected by sensor S (which in turnprovides indicia of saturation in that no additional changes in thearomatic concentration are occurring), the controller 170 in response tosuch an acquired signal switches the market fuel M that is beingdelivered from supply tank 220 to the second reaction chamber 244. In asecond technique, a timer is connected to the controller 170 to allow itto open and close at certain time intervals (for example every 15minutes) where the time intervals depend on the adsorbent 242A, 244Asize and rate of the adsorption. In a third technique, sensor S may be atemperature sensor such that once the temperature at the respectivereaction chamber 242, 244 is no longer increasing (which in turnprovides indicia of no further heat release due to adsorption), thecontroller 170 switches the fuel flow from the first reaction chamber242 to the second reaction chamber 244. Thus, under such batch-basedoperation, the two-chamber construction of the separation unit 240 issuch that while adsorption of a portion of the market fuel M is takingplace in reaction chamber 242, any adsorbent 242A, 244A that waspreviously saturated in the other reaction chamber 244 is regenerated byexposure of the adsorbate A to the solvent V. As mentioned previously,with a different choice in adsorbent 242A, 244A in the reaction chambers242, 244, a cetane-rich adsorbate A_(C) (rather than an octane-richadsorbate A_(O), both of which are shown generally as residing withinthe volumetric space defined by the first and second reaction chambers242, 244) can be formed in a comparable manner. For example, in oneform, materials such as Carbopack B (manufactured by Supelco Inc. ofBellefonte, Pa.) and graphitizied carbon black may be used to provide acetane-attracting functional-group adsorbent.

In one form, the first of the reaction chambers 242 is sized and shapedto fluidly receive an aromatic (that is to say, octane-rich) compoundcontained within the market fuel M such that contact of the aromatic onthe surface of reaction chamber 242 results in the creation of theoctane-rich adsorbate A_(O) for OOD. It will be appreciated that relatedfunctionality fuel components such as oxygenates or double bond-basedalkyls may also fall within the category of compounds or fuel componentsthat can provide OOD. In such form, the preferential action of asuitable functional group contained within or formed on the surface ofthe adsorbent 242A that makes up the reaction chamber 242 provides thenecessary separation. In this form, the operation of the tank 232,solvent regeneration unit 236 and conduit 238 causes the adsorbate A tobe desorbed and released to an octane-rich one of the enriched producttanks 250, 260 for subsequent use in the combustion chamber 156 insituations where the market fuel M is a higher boiling point (forexample, between about 165° C. and about 350° C.) diesel-type fuel. Witha different choice in adsorbent 242A, 244A (for example, a sizeselective version) from the solvent supply 230 being circulated throughthe reaction chambers 242, 244, a cetane-rich adsorbate A_(C) forcombustion chamber 156 is created; such an approach may be used insituations where the market fuel M is a lower boiling point (forexample, between about ambient temperature and about 200° C.)gasoline-type fuel. As such, the reaction chambers 242, 244 may—inaddition to having batch processing capability discussed previouslythrough selective adsorbing and desorbing activities—be set up in stages(not shown) in the manner previously discussed such that a first stagepreferentially provides one or the other of affinity-based or sizeselective-based adsorption while a second stage provides the other ofthe size selective—based or affinity-based adsorption. Such staging maytake place sequentially, in either common or separate housing, in amanner suitable to ensure relatively small volumetric packaging neededto fit as unobtrusively as possible within vehicle 100. It will beappreciated that the order of separation achieved by such staging may beaffinity-based first and size selective second, or size selective firstand affinity-based second, depending on the need.

In one form, the fuel system 200 is particularly configured to operateon a market fuel M that can provide energy for a CI mode of operation.Thus, unlike in situations where the boiling range of the separated fuelstream is within a range that is compatible with heat exchange valuesthat can be provided by the operation of the ICE 150 (such as the casewhen the market fuel M includes significant gasoline fractions), whenthe separated stream has low volatility (that is to say, high boilingpoint) such as the case when separating diesel fuel fractions, then thehigh temperature needed to perform such regeneration is either notreadily available onboard vehicle 100 or is such that the separatedcomponent could be prone to cracking at the high temperatures requiredto perform such regeneration of solvent V. In this way, the solvent Vand the cetane-rich adsorbate A_(C) may then be separated by a one-stepmethod in the solvent regeneration unit 236 such as discussed elsewherein this disclosure. Such separation may be enhanced by selecting thesolvent V to have much different volatility than the cetane-richadsorbate A_(C). It will be appreciated that the fuel system 200—workingin conjunction with controller 170—may be configured to operate ineither of both of an OOD mode of operation or a COD mode of operationdepending on one or more of the affinity and size of the adsorbent 242A,244A such as those discussed previously.

In one form, the solvent supply 230 may be disposed within the housingor related containment structure that makes up the separation unit 240,while in another, it may be placed outside such housing such that assolvent V is needed to perform the desorbing operation from one or bothof the reaction chambers 242, 244, it can be delivered from the solventsupply 230 through suitable conduit 238 as previously discussed. As withthe packaging used to reduce space for the solvent supply 230, theadsorbent 242A, 244A type may be selected to promote small housing orcontainment structure size. In one form, if the adsorbent 242A, 244Aemploys a high surface area-to-volume ratio by exploiting the geometryand structure of particles and bed that make up the two reactionchambers 242, 244, such higher surface area may lead to higheradsorption capacity and smaller separation unit 240 size as a way topromote ease of system integration.

As mentioned previously, various forms of stratified combustion may leadto the types of LTC that are beneficial to low-NO_(X) operation of ICE150. With regard to the use of OOD or COD for a CI mode of operation,the fuel may be formed as a hybrid of a main fuel (for example, gasolineor other low-cetane variant) and an igniter fuel (for example, diesel orother high-cetane variant), where the location, frequency and timing ofintroduction of each varies by concept or configuration such as thosediscussed previously. For example, in one concept, a single high-octanefuel is introduced via direct injection during a compression stroke. Insuch case, the injection of the fuel may take place at a time relativelyretarded from conventional diesel injection timing to ensure adequatemixing. Since the overall combustion process is dominated byreactivity-controlled LTC, the resulting NOx and soot exhaust emissionstend to be very low. In another case, a single igniter fuel isintroduced via direct injection during the compression stroke in orderto promote cold-start and high-load operation where the overallcombustion process is dominated by diffusion-controlled mixing of thefuel at or near the piston 162 TDC movement. In still another case, adual injection regime introduces the main fuel via port fuel injectionearly in the compression stroke within the combustion chamber 156 suchthat it is fully mixed with a fresh air charge during the intake stroke,after which the igniter fuel is introduced via direct injection as a wayto control ignitability such that the overall combustion process isdominated by the spatially well-mixed high-octane fuel after theignition of high-cetane fuel. As with the first case mentionedpreviously, such operation produces low NOx and soot emissions, due atleast in part to an overall lean mixture. In yet another case, the mainfuel is introduced via direct injection during the compression stroke,while the igniter fuel is introduced via direct injection near TDC toenable the ignition control; in this way, it provides a relativelyrobust mixture via improved thermal or spatial stratification. This inturn leads to low hydrocarbon, NOx and soot formation, at least forrelatively low engine loads.

In one form, a so-called bypass may be used for intermittentcircumstances associated with various ICE 150 operating environments(such as cold starts, or where one or both of the two enriched producttanks 250, 260 may be empty) such that at least a fraction of the marketfuel M from the supply tank 220 is provided directly to the combustionchamber 156 without entering the separation unit 240. This bypassoperation may be established by controller 170 to help promote acontinuous supply of fuel to ICE 150, where such continuity isparticularly useful under these intermittent operational conditions. Inparticular, the controller 170 may be used to manipulate various fueldelivery parameters, such as coolant temperature, exhaust gastemperature, EGR, exhaust gas re-breathing, level of separated fuels,delivery timing or the like for such transient conditions. This helpspromote wider operating ranges based on reactivity differences betweenthe high-octane and high-cetane fuel components. This wider operatingrange is especially beneficial with regard to reducing NOx or sootemissions regardless of factors such as ICE 150 load, operatingtemperature, fuel delivery or the like. This in turn reduces thelikelihood of having to make emissions or performance tradeoffs (such asa soot/NOx tradeoff), where factors such as temperature and engineequivalence ratio can otherwise force the controller 170 to determinewhich of two or more competing ICE 150 operating conditions should bepermitted to operate. Such operating range is also beneficial in that itpermits various other fuel injection strategies to be utilized to enableoptimum efficiency, reduced emissions and improved combustion robustnesscompared to conventional SI-based or CI-based cycles, including usingEGR, reduced compression ratios or the like as part of a larger LTCstrategy.

As previously discussed, in one form the adsorbents 242A, 244A used forthe reaction chambers 242, 244 are configured as one or more functionalgroups presenting on the surface of the sorbent material such that theycomprise affinity-based sorbents. In another form, the adsorbents 242A,244A may separate adsorbates A by their molecular shape such that theycomprise size selective sorbents. For example, to target high-cetanefuel components, the design would focus on separating linear or slightlybranched alkanes from aromatics, cyclic and highly branched alkanes.Stated another way, the sorbents can act in two mechanisms, where in afirst, the adsorbent 242A, 244A is selected to have functional groupsthat attract specific molecules such as aromatics, cyclic, (andoxygenates if present). The linear and slightly branched molecules(which may include cetane) are not adsorbed and pass through the poresof one or both of the reaction chamber 242, 244, depending on their modeof operation. The second mechanism is based on the difference in themolecules sizes such that linear molecules (such as n-alkanes) may passthrough the relatively porous material while other molecules which havea larger dynamic diameter (such as highly-branched alkanes) are hinderedfrom passing through most pores and accumulate in the adsorption-basedreaction chamber 242, 244. In this latter mechanism, a packed bed ofsize selective sorbent may be used for COD generation, as linear alkaneswith high CN will go into smaller pores while the other components withlarger molecular size will not, causing these other components to comeout first as a raffinate. Moreover, in configurations where theadsorbent 242A, 244A acts as a molecular sieve, it may be made up ofmore than one particle type or size in order to preferentially promotethe adsorption of a desired species based on the size of such species.Regardless of the adsorbent 242A, 244A choice, the performance isoptimized on various factors, including the capacity and selectivity ofthe adsorbent 242A, 244A, the concentration ratio of the market fuel M(which provides indicia of the aromatics fractions), and how fast thesolvent V regeneration and desorption-based removal proceeds.

Specific surface area (that is to say, the total surface area of a givensubstance per unit mass, for example, in m²/g) is a valuable metric inassessing the efficacy of an adsorbent such as adsorbent 242A, 244A. Inparticular, increasing the specific surface area of the adsorbent 242A,244A permits a higher adsorption capacity. For example, when usingactivated carbon with specific surface area ranging in size from 500 to1500 m²/g, the adsorption capacity correspondingly increases, as well aswith the adsorbed molecule type. Thus, adsorbents 242A, 244A withdifferent specific surface areas can be used to selectively adsorb oneor the other of a desirable component within the market fuel M, and allsuch variants are deemed to be within the scope of the presentdisclosure. For example, the specific surface area may be tailored toadsorb low boiling point straight alkanes as a way to produce thecetane-rich adsorbate A_(C) that can act as a high ignition qualitybooster for the market fuel M in a CI mode of operation. Likewise, thespecific surface area may be tailored to adsorb aromatics as a way toproduce the octane-rich adsorbate A_(O) that can act as a high ignitionquality booster for the market fuel M in an SI mode of operation. Forinstance, to adsorb certain aromatics, the adsorbent 242A, 244A thatmakes up the reaction chambers 242, 244 can be mesoporous (2-50 nmdiameter) activated carbon, which in turn can lead to an averagerecovery of about 80%. An example of the anticipated adsorption capacityof some aromatic components for activated carbon is listed in Table 1.

TABLE 1 Component mg/g-adsorbent Toluene 15 Naphthalene 451-methylnaphthalene 37

Other natural adsorbents (for example, coconut shell) may also be usedfor separating the desired components. In another form, the surface ofthe reaction chambers 242, 244 may define one or more beds that may bemade up of more than one adsorbent 242A, 244A in order to preferentiallypromote the adsorption of a desired species. Regardless of the adsorbent242A, 244A bed choice, the performance is optimized on various factors,including the adsorbent 242A, 244A capacity and selectivity, theconcentration ratio of the market fuel M (which provides indicia of thearomatics fractions), and how fast the regeneration and desorption-basedremoval proceeds.

With particular regard to the bypass mentioned previously, in certainoperating environments of ICE 150, it may be necessary for reliablecombustion to not use the separation unit 240, but to instead useconventional modes of operation such as those associated withtraditional diesel-based CI or gasoline-based SI, as at startup or otherscenarios there are no exhaust gases or hot radiator fluid available toheat the adsorption cycle, or where there are no high-cetane orhigh-octane fuels present in the enriched product tanks 250, 260. Withinthe present context, this operating environment that corresponds tohaving neither an adequate amount of heat (such as the residual thataccompanies the ICE 150 combustion process, as well as any supplementalsource of heat such as that associated with an electric heater, separatecombustor or the like) nor onboard supply of cetane-rich or octane-richfuel components is referred to as the bypass condition. In the bypasscondition, the controller 170 may direct the supply of fuel to beconveyed from the market fuel supply tank 220 and directly to thecombustion chamber 156 of ICE 150 so that a suitable CI or SI mode ofoperation may be undertaken without having to rely upon the productionor use of the additional octane-rich or cetane-rich fuel components asproduced by the separation unit 240 and solvent supply 230. Contrarily,an operating environment that corresponds to having one or both anadequate amount of heat (such as the residual that accompanies the ICE150 combustion process) and onboard supply of cetane-rich or octane-richfuel components is referred to as the adsorption condition; in thislatter condition, varying amounts of additional octane-rich orcetane-rich fuel components may be produced, used in the combustionprocess, or both. The bypass condition of ICE 150 means that the bypassmay be used to avoid otherwise undesirable latency periods associatedwith sudden driving operations in response to speed or load demands, aswell as those related to temperature or related weather conditions. Insuch circumstances, the controller 170 may instruct some or all of themarket fuel M from supply tank 220 to be supplied directly to thecombustion chamber 156, without entering the separation unit 240. Thefraction of bypass can be controlled and manipulated via differentmethods such as temperature of the coolant or exhaust gas, level ofseparated fuels, time or other variables. Likewise, the controller 170may in one form optionally mandate that under this bypass condition, theSI mode of operation be employed, while in another optional form maypermit the CI mode of operation to proceed, such as those associatedwith the market fuel supply tanks 220 containing diesel fuel.

Two examples are presented to highlight when the bypass operation thatmay take place when the operating environment of the ICE 150 iswarranted. In a first example, during startup of ICE 150 wheninsufficient heat is available to properly operate an adsorptionoperation within the separation unit 240, the controller 170 workstogether so that fuel flow to the combustion chamber 156 may partiallycome from the two enriched product tanks 250, 260, while the main fuelportion comes from the market fuel supply tank 220. In a second example,if either of the two enriched product tanks 250, 260 is empty at anytime (such as that associated with unexpected driving cycle conditions,lack of solvent-based elution of the adsorbate A needed for desorptionor other event that would leave the enriched product tanks 250, 260empty or nearly empty), the controller 170 may likewise instruct one ormore fuel pumps 270 (only one of which is shown) to pressurize themarket fuel M being delivered from the supply tank 220 directly to thecombustion chamber 156 as a way to at least partially bypass theseparation unit 240 to compensate for the shortage in the enrichedproduct tank 250 or the enriched product tank 260 where it will beunderstood that one or the other of the enriched product tanks 250, 260is configured to contain an octane-rich fuel component while the otheris configured to contain a cetane-rich fuel component, depending onwhether the adsorbent 242A, 244A that is being introduced into thereaction chambers 242, 244 is an affinity-based one or a sizeselective-based one. Thus, in one form, the enriched product tank 250contains a high RON fuel while the enriched product tank 260 contains ahigh CN fuel, whereas in another form, the enriched product tank 250contains a high CN fuel while the enriched product tank 260 contains ahigh RON fuel. In situations where both cold engine conditions and lowenriched product tank 250, 260 levels are present, the bypass may becomplete rather than partial, and may accompany an SI or conventionaldiesel-based CI mode of operation as well.

Having described the subject matter of the present disclosure in detailand by reference to specific embodiments thereof, it is noted that thevarious details disclosed in the present disclosure should not be takento imply that these details relate to elements that are essentialcomponents of the various described embodiments, even in cases where aparticular element is illustrated in each of the drawings that accompanythe present description. Further, it will be apparent that modificationsand variations are possible without departing from the scope of thepresent disclosure, including, but not limited to, embodiments definedin the appended claims. More specifically, although some aspects of thepresent disclosure are identified as preferred or particularlyadvantageous, it is contemplated that the present disclosure is notnecessarily limited to these aspects.

It is noted that one or more of the following claims utilize the term“wherein” as a transitional phrase. For the purposes of definingfeatures discussed in the present disclosure, it is noted that this termis introduced in the claims as an open-ended transitional phrase that isused to introduce a recitation of a series of characteristics of thestructure and should be interpreted in like manner as the more commonlyused open-ended preamble term “comprising.”

It is noted that terms like “preferably”, “generally” and “typically”are not utilized in the present disclosure to limit the scope of theclaims or to imply that certain features are critical, essential, oreven important to the disclosed structures or functions. Rather, theseterms are merely intended to highlight alternative or additionalfeatures that may or may not be utilized in a particular embodiment ofthe disclosed subject matter. Likewise, it is noted that the terms“substantially” and “approximately” and their variants are utilized torepresent the inherent degree of uncertainty that may be attributed toany quantitative comparison, value, measurement or other representation.As such, use of these terms represent the degree by which a quantitativerepresentation may vary from a stated reference without resulting in achange in the basic function of the subject matter at issue.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the described embodimentswithout departing from the spirit and scope of the claimed subjectmatter. Thus it is intended that the specification cover themodifications and variations of the various described embodimentsprovided such modification and variations come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A vehicular propulsion system comprising: aninternal combustion engine comprising at least one combustion chamber;and a fuel system comprising: a fuel supply tank for containing anonboard fuel; fuel conduit in fluid communication with the fuel supplytank; a separation unit in fluid communication with the fuel supply tankthrough the fuel conduit, the separation unit comprising at least oneadsorbent-based reaction chamber that is configured to selectivelyreceive and separate at least a portion of the onboard fuel into anadsorbate and a remainder; a solvent supply in fluid communication withthe separation unit and containing at least one solvent therein toconvert at least a portion of the adsorbate into a desorbate; a solventregeneration unit configured to separate at least a portion of the atleast one solvent from the desorbate; a first enriched product tank forreceiving and containing the portion of the desorbate that has beenseparated from the at least one solvent; and a second enriched producttank for receiving and containing the remainder, wherein duringoperation of the internal combustion engine, the fuel system is in fluidcommunication with the internal combustion engine such that at least oneof the fuel supply tank and the first and second enriched product tanksprovide their respective onboard fuel, separated desorbate and remainderto the combustion chamber.
 2. The vehicular propulsion system of claim1, wherein the at least one reaction chamber contains an affinity-basedadsorbent.
 3. The vehicular propulsion system of claim 1, wherein the atleast one reaction chamber contains a size selective-based adsorbent. 4.The vehicular propulsion system of claim 1, wherein the at least onereaction chamber contains both an affinity-based adsorbent and a sizeselective-based adsorbent.
 5. The vehicular propulsion system of claim1, wherein operation of the internal combustion engine defines aplurality of operational conditions such that while in a firstoperational condition at least a portion of the onboard fuel is conveyedto the combustion chamber without first passing through the separationunit, and while in a second operational condition at least a portion ofthe onboard fuel is conveyed to the combustion chamber after havingpassed through the separation unit and at least one of the first andsecond enriched product tanks.
 6. The vehicular propulsion system ofclaim 5, further comprising a controller cooperative with the fuelsystem to selectively convey at least one of the onboard fuel, separateddesorbent and remainder to the combustion chamber.
 7. The vehicularpropulsion system of claim 6, further comprising a plurality of sensorsthat are configured to acquire operational parameters associated withthe internal combustion engine and the fuel system such that thecontroller is additionally cooperative with at least one of the sensorsto process at least one of the acquired operational parameters in orderto determine whether the internal combustion engine is in the firstoperational condition or the second operational condition such that thecontroller directs the fuel system to convey at least one of the onboardfuel, separated desorbate and remainder to the combustion chamber inresponse to the determined operational condition.
 8. The vehicularpropulsion system of claim 1, wherein the solvent regeneration unit isconfigured to perform liquid-liquid extraction.
 9. The vehicularpropulsion system of claim 1, wherein the solvent regeneration unit isconfigured to perform extractive distillation.
 10. A vehicular fuelsystem for converting an onboard fuel into octane-rich and cetane-richcomponents, the fuel system comprising: a fuel supply tank forcontaining the onboard fuel; fuel conduit in fluid communication withthe fuel supply tank; a separation unit in fluid communication with thefuel supply tank through the fuel conduit, the separation unitcomprising at least one adsorbent-based reaction chamber that isconfigured to selectively receive and separate at least a portion of theonboard fuel into an adsorbate and a remainder; a solvent supply influid communication with the separation unit and containing at least onesolvent therein to convert at least a portion of the adsorbate into adesorbate; a solvent regeneration unit configured to separate at least aportion of the at least one solvent from the desorbate; a first enrichedproduct tank for receiving and containing the portion of the desorbatethat has been separated from the at least one solvent; and a secondenriched product tank for receiving and containing the remainder. 11.The vehicular fuel system of claim 10, further comprising: a pluralityof sensors configured to acquire operational parameters associated withthe operation of the fuel system and of an internal combustion enginethat is fluidly coupled to the fuel system; and a controller cooperativewith at least one of the fuel supply tank, fuel conduit, separationunit, first and second product tanks and plurality of sensors andconfigured to determine an internal combustion engine operationalcondition such that when the controller determines a first operationalcondition, the controller is configured to direct the flow of a portionof the onboard fuel to such an engine without first passing through theseparation unit, and when the controller determines a second operationalcondition, the controller is configured to direct the flow of a portionof the onboard fuel to the separation unit.
 12. The vehicular fuelsystem of claim 10, wherein the cooperation between the separation unit,solvent supply and solvent regeneration unit is such that a substantialentirety of the production of the desorbate takes place by a chemicalreaction between the at least one solvent and the portion of the onboardfuel within the separation unit.
 13. The vehicular fuel system of claim10, wherein the production of the desorbate and its separation from theat least one solvent takes placed in a closed-loop system comprising thesolvent supply, solvent regeneration unit and at least one the reactionchamber.
 14. A method of producing fuel for an internal combustionengine that is used to provide propulsive power to a vehicle, the methodcomprising: conveying onboard fuel to a separation unit that makes up aportion of a fuel system; contacting the fuel with an adsorbent situatedwithin the separation unit such that at least a portion of the fuel isconverted into an adsorbate and at least a portion of the fuel isconverted into a remainder; reacting at least one solvent with theadsorbate such that at least a portion of the adsorbate is convertedinto a desorbate; separating the desorbate from the at least onesolvent; and conveying at least one of the onboard fuel, separateddesorbate and remainder to a combustion chamber within the internalcombustion engine.
 15. The method of claim 14, wherein the separateddesorbate is conveyed to a first enriched product tank prior to beingconveyed to the combustion chamber.
 16. The method of claim 14, whereinthe remainder is conveyed to a second enriched product tank prior tobeing conveyed to the combustion chamber.
 17. The method of claim 14,further comprising: sensing at least one operational parameterassociated with the fuel system and the internal combustion engine; andusing a controller to determine an engine operational condition that isselected from a plurality of operational conditions based on the atleast one sensed operational parameter such that the conveying at leastone of the onboard fuel, separated desorbate and remainder to acombustion chamber within the internal combustion engine is performedbased on the determined operational condition.
 18. The method of claim17, wherein the engine operational condition comprises: a firstoperational condition such that at least a portion of the onboard fuelis conveyed to the combustion chamber without first passing through theseparation unit; and a second operational condition such that at least aportion of the onboard fuel is conveyed to the combustion chamber afterhaving passed through the separation unit.
 19. The method of claim 18,wherein the first operational condition corresponds to a temperature ofthe internal combustion engine that is indicative of at least one of acold start and a warm-up, and further wherein the second operationalcondition corresponds to an engine temperature that exceeds the coldstart and warm-up engine temperatures.
 20. The method of claim 18,wherein the first operational condition of the engine corresponds to asituation where at least one of first and second enriched product tanksthat are used to contain a respective separated desorbate and remainderis substantially empty.